The current invention relates to methods of forming a sealing system for a reclosable package, and the package made. In particular, it relates to a system for a package having walls of film or the like, typically formed from one or two webs sealed at the edges, the package having a reclosable seal and a peel seal.
There has been recent interest in expanding the use of reclosable seals of the interlocking type, which typically are of the rib and groove type often informally called a zipper.
Seals of this type are disclosed in U.S. Pat. No. 2,978,769 of Harrah, U.S. Pat. No. 3,198,228 of Naito and U.S. Pat. No. 4,212,337 of Kamp.
Zipper seals may be manufactured in advance as elements that may be called "profile strips" and later attached to webbing, as shown in U.S. Pat. No. 3,948,705 of Ausnit. In the alternative, the seals may be co-extruded together with one or more film members that will form the walls of the package.
It is presently preferred for such profile strips to be manufactured of polyethylene. Not only is polyethylene less expensive than many other materials typically used in this technology, but it does not take a strong set. That is, when manufactured in advance the profile strips may be wound on a spool or the like and, when unwound later, do not strongly tend to resume the wound shape. This provides a significant advantage.
Also in the past, packages have been provided having additional seals to complement interlocking seals. Such packages are shown in U.S. Pat. No. 3,181,583 of Lingenfelter (rupturable tear line) and U.S. Pat. No. 4,246,288 of Sanborn, Jr. (hermetic seal).
Second seals specifically made of peelable material are shown in U.S. Pat. No. 4,782,951 of Griesbach et al. (used in connection with interlock closure strips 14) and U.S. Pat. No. 4,786,190 of Van Erden et al. (used in combination with reclosable pressure sensitive adhesive 29).
Especially in the case where peelable material is used to provide a seal, it is desirable to minimize the amount of such material used. It is costly in comparison to other seal materials used in this technology.
As known in the art, the so-called "peelable material" referenced above is used to make a non-reclosable seal called a "peel seal." Certain materials, typically of resinous composition, are known to react in such a manner that they can be used in combination either with a dissimilar material or with additional material of the same composition to produce such seals. Therefore, whether or not a seal is peelable depends upon the materials used. This specification uses the term "peelable material" to describe a single element of such material, but it will be understood by those skilled in the art that the term refers to such a material when used together with additional material of the same or different composition in order to produce a peel seal.